Current effort for the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) program is to bring new technology, new architecture and new methods in the new LTE settings and configurations in order to provide improved spectral efficiency, reduced latency, better utilizing the radio resource to bring faster user experiences and richer applications and services with less cost.
LTE packet data convergence protocol (PDCP) is now responsible for ciphering, integrity protection and PDCP service data unit (SDU) sequence number (SN) maintenance. While PDCP Data protocol data units (PDUs) are ciphered, LTE specifications do not allow for ciphering and integrity protection of PDCP Control PDUs.
Peer PDCP entities can exchange PDCP-STATUS messages, for instance during a handover. A PDCP-STATUS message indicates whether or not one or more PDCP SDUs has been received by the receiving PDCP entity (i.e. it provides positive or negative acknowledgements for PDCP SDU SN(s)). A PDCP-STATUS message may be sent using a PDCP Control PDU.
PDCP operations have already evolved beyond the previous Universal Mobile Telecommunication Systems (UMTS) realm. As a result, PDCP Control PDUs are available to assist special operations as well as to regulate the normal operation management tasks. To this end, the PDCP Control PDU operations need to be defined and standardized in order to coordinate the actions between the peer PDCP entities.